The new cultivar was discovered as a result of a planned breeding program directed by the inventor, Luc Decourtye, a citizen of France. ‘Courtacad1’ is a selection from a planned breeding program. First the breeder conducted a cross-pollination of Weigela hybrid ‘Mansais’ (unpatented) as the female parent, and Weigela florida ‘Foliis Purpureis’ (unpatented) as the male parent. This initial cross-pollination of the parent plants took place in Beaucouzé, France in 1987. Subsequently, the F1 generation resulting from the 1987 cross was self-pollinated and seed collected and planted during the following year. From these F2 seedlings a selection was made of the seedling now referred to as ‘Courtacad1’ in 1989, by the inventor in a research nursery in Beaucouzé, France. The exact seed and pollen parents are unknown.
Asexual reproduction of the new cultivar ‘COURTACAD1’ was first accomplished in 2006 by vegetative cuttings at a research nursery in Angers, France. Multiple generations have since been produced and have shown that the unique features of this cultivar are stable and reproduced true to type in successive generations.